1. Field of the Invention
The present invention relates to a light source apparatus outputting light that has been amplified in an optical amplifier waveguide.
2. Related Background Art
Light source apparatuses, which amplify light by use of optical amplifier waveguides, have been applied in the respective fields of laser machining, communications, measurements, and the like. In these fields, it is useful to realize an optical pulse with a narrow pulse width and high peak power. Fiber lasers or fiber amplifiers are compact optical devices capable of performing high-efficiency optical amplification, and have a beam quality substantially diffraction-limited, having received a great deal of attention.
In an optical device in which optical fibers are applied as amplifying transmission paths as described above, when the peak power of output light is increased, a nonlinear effect (stimulated Raman scattering (SRS), stimulated Brillouin scattering (SBS), or the like) occurs in the optical fiber. Such a nonlinear effect brings a negative effect such as deterioration of a pulse waveform of an output light. In particular, in the practical use of a high-power outputted optical pulse, not only an optical amplifier waveguide, but also an optical output waveguide (so-called delivery fiber) to guide a light from the optical amplifier waveguide to an output end is preferably lengthened as much as possible. Accordingly, there is further concern that a nonlinear effect occurs. There is recorded in J. Limpert et al., “Sub-10 ns Q-switched Yb-doped photonic crystal fiber laser,” CLEO2005, JWB51 (Document 1) a case in which an attempt is made to suppress a nonlinear effect by using a particular optical amplifier fiber with a core diameter of 35 μm in order to avoid such a nonlinear effect.